prompt = "请输入你的年龄:"
prompt += "(输入quit退出循环)"
active = True
while active:
    age = input(prompt)
    if age == 'quit':
       # active == False
       break
    elif age != 'quit':
        age_int = int(age)
        if age_int < 3:
            print("免费")
        elif age_int <= 12:
            print("10美元")
        else:
            print("15美元")
